20 Ways to Get Better Gas Mileage

The average American drives about 13,500 miles each year, according to the U.S. Department of Transportation, and gas prices are significantly higher than a year ago — about 60 cents a gallon. So fuel efficiency remains of critical importance. Squeezing more miles out of every gallon means you'll spend less money on fuel while helping to conserve a limited natural resource and reduce the greenhouse gas emissions that play a role in climate change. Cheapism has identified 20 ways drivers can get more miles to the gallon.

An important starting point is tracking your current miles per gallon (mpg). There are apps for this, but it's a simple back-of-the-napkin calculation. After filling up at the pump, save the receipt and record the current odometer reading. At the next fill up, divide the miles driven since the last reading by the gallons pumped to determine the mpg. Do this several times to find the average.

The U.S. Department of Energy estimates that aggressive driving lowers gas mileage by up to 33 percent on the highway and 5 percent in the city. Take a deep breath and focus on accelerating and braking slowly and staying at or under the speed limit. Using cruise control may help, as it limits unnecessary braking and accelerating.

The more weight the engine has to move, the more gas it consumes. Spend an afternoon cleaning out the trunk and getting rid of any other superfluous weight. If the vehicle has removable seats that are used rarely, consider storing them in the garage.

Likewise, roof racks and other storage accessories will increase drag on your vehicle when you're driving. If you're not actually using them, remove them to keep you car as aerodynamic as possible. This goes for bike and ski racks, too. And if you're driving a pickup, keeping the tailgate up appears to improve mileage, not lower it, something that will come as a surprise to many pick-up drivers.

Traffic is more than just a nuisance — idling cars burn gas and waste money. Some new, upmarket cars address this problem by switching off the engine when the car comes to a stop and automatically restarting when the gas pedal is depressed. But this is a luxury many drivers can't afford. Instead, opt for side roads when the highway is congested or find a way to avoid the rush hour all together. Join a gym near work and arrive an hourly early to work out and shower, or find a social event or professional development opportunity held after work several times a week.

Underinflated tires decrease fuel efficiency and also are downright dangerous. The National Highway Traffic Safety Administration estimates that tire failure results in 11,000 crashes a year and says that maintaining proper tire pressure (look inside the vehicle's door or in the owner's manual) is the most important part of tire safety. This is a concern especially during the hot summer months when the added heat can lead to blowouts and tread separations. For every 1 psi (pounds per square inch) below the recommended tire pressure, fuel efficiency decreases by 0.3 percent. This is a per-tire calculation, meaning if all four tires are under-inflated the overall loss can be significant.

Owners should check the tire alignment every few years. If the alignment is off, the wheels will hit the road at odd angles causing unbalanced wear, which decreases the tires' lifespan and lowers fuel efficiency. An alignment check and adjustment cost about $75.

When it's hot out, the windows go down or the AC is turned on. Both decrease fuel efficiency, but it's a price most drivers are happy to pay. Which is worse on the wallet? The website MythBusters put the quandary to a test and found that down windows burned up less fuel than air conditioning. On the other hand, Edmunds.com found no significant difference between using the AC and rolling down windows. The jury is still out, but a good rule of thumb is to open windows when driving slowly (below 40 mph) and use the forced cool air while driving at higher speeds. Extra tip: Cooling off the car first with open windows means the AC won't have to work as hard once it's turned on.

Drivers whose cars have manual transmission can take advantage of the added control to decrease fuel consumption. By shifting to a higher gear as early as possible, the engine turns slower and uses less gasoline. The downside of this tactic is that the vehicle won't accelerate as quickly.

Anyone who has driven in Hawaii knows that "island time" means driving at or below the speed limit, even when it's 45 mph. Drivers on the mainland who want to save on gas should follow suit. Fuel efficiency starts to drop off drastically when driving above 50 mph. The Department of Energy estimates that each 5 mph above 50 is equivalent to paying an extra 7 percent for each gallon of gas. Cruise control is a good way to keep speed in check.

When climbing a hill, putting the pedal to the metal can push miles per gallon down to the single digits. Focus on maintaining, rather than increasing, speed and accept that it's okay to go slightly slower on the way up.

After cresting a hill, use the power of gravity to go as far as possible. Coasting means infinite miles per gallon. The news organization Mother Jones reports on one man who takes coasting to the extreme. In a demonstration ride, he exited a freeway at 50 mph, turned off the engine, and traveled more than mile using the pent-up energy.

Some people occasionally treat their vehicle to a tank of premium gasoline, but automotive experts at Edmunds.com say that's a waste of money. At one time, premium gas contained engine-cleaning additives that regular gas did not, but subsequent regulation has made standard gasoline just as good. Even drivers whose vehicles ostensibly need premium, according to the manufacturer's recommendation, can switch to regular with no ill effects and save money, as well.

It's important to ensure your gas cap fits snugly when you put it back after fueling. Also make sure that its seals are not damaged or worn out. Otherwise your gas can evaporate into the atmosphere, where it benefits no one. One clue your gas cap might be failing: The vehicle's check engine light is on. A bad cap can affect a vehicle's emissions system, also affecting mileage.

If you're driving an older vehicle, especially one with a carburetor, a dirty air filter can tax your engine and seriously impact mileage. Make sure it's not clogged. Air filters are cheap, and they are also an important way to keep your engine clean.

If spark plugs are corroded or misfiring for any reason, mileage will suffer. Replace them according to your vehicle's recommended maintenance schedule and your driving habits. When you replace the plugs, it's generally a good idea to replace the spark plug wires, too.

Clogged or dirty fuel injectors will also tamp down mileage. If your vehicle experiences a lag in mileage, they may need to be cleaned professionally. Meantime, it might be worth it to occasionally add a fuel-injector cleaning product to your gas to stave off such problems.

A rough-idling engine, significantly bad mileage, and a vehicle's illuminated check engine light are all symptoms that will cheerfully inform you this may need to be done. Eventually these sensors and others do wear out.

Old, sludgy, worn-out motor oil will affect mileage and not in a positive way. Keeping your vehicle's oil changed at the manufacturer's recommended interval will avoid this, and using the carmaker's recommended grade of oil is key and can improve mileage by up to 2 percent. Switching to synthetic motor oil can also improve mileage. Typically synthetic oils cost more, but they also last longer.

A properly warmed-up engine runs more efficiently than one that just started cold. So take advantage of this by making one longer trip than several shorter trips.

The last tip may be the most obvious, but is still worth pointing out. When shopping for a new car, consider its fuel efficiency. Depending on daily driving habits and conditions, a few extra miles per gallon can make a big difference. Small and lightweight cars often do best, but there are efficient hybrid and pure electric SUVs on the market, as well.